This invention relates generally to the field of automatic CNC (Computerized Numerical Control) turning lathes, and more particularly to the field of chucks and collet guides used to retain or position workpieces during the cutting operations. Even more particularly, the invention relates to an adaptor device which allows an automatic CNC turning lathe with a sub-spindle to be converted to a lathe capable of performing Swiss-type machining.
There are two basic types of automatic CNC turning lathes used to shape parts from elongated cylindrical or tubular stock. The first utilizes a stationary headstock and a chuck which grips and rotates the workpiece stock while the cutting bits are moved radially and longitudinally along the length of the workpiece, the workpiece itself remaining stationary in the longitudinal direction. The second, known as the Swiss-type sliding headstock automatic lathe, utilizes a non-stationary headstock and a chuck which grips, rotates and feeds the workpiece stock longitudinally while the cutting bit remains stationary in the longitudinal direction and moves only in the radial direction to machine the workpiece. The Swiss-type sliding headstock lathe utilizes a stationary guide bushing in front of and aligned with the sliding headstock chuck to guide and support the workpiece stock. Different machining operations dictate which type of automatic CNC lathe is preferred for producing a particular part. The Swiss-type sliding headstock lathe is preferred for production of long, small diameter parts such as needles, since all cutting occurs near the guide bushing end where the workpiece is supported against the deflective forces of the cutting bit by the guide bushing and the opposite end of the workpiece is supported by the sub-spindle.
It is an object of this invention to provide an adaptor device which can be mounted onto an automatic CNC turning lathe with a sub-spindle which allows the lathe to perform Swiss-type turning. It is a further object to provide such a device which does not require extensive alteration of the chuck of the automatic CNC lathe, and which allows the radial jaws of the automatic CNC lathe to operate unhindered.